Unlike the traditionally discussed language types which either allow subject NP omission throughout (as do Italian and Chinese) or not at all (English or Swedish), the two languages described here are mixed languages. In Hebrew and Finnish, subject NPs can be omitted in certain persons or tenses, but not in others. In these languages omission of 1st and 2nd person subjects is common (as in Italian and Chinese), but in the 3rd person an overt subject NP is required (as in English and Swedish). This situation holds for all tenses in Finnish, and for tenses other than the present tense in Hebrew, where a subject NP is required in all persons. The contribution of this paper is to provide an analysis of null subjects which both covers the complicated mixed systems of Hebrew and Finnish and extends to the systems of null subjects traditionally discussed in the literature. The analysis is based on the idea that the syntactic position of subject-verb agreement features varies cross-linguistically, and even within a language. Thus, in the English-type languages an overt subject is required to license the subject position, whereas in the Italian-type languages subject-verb agreement features occupy the subject position, and no overt subject NP is required. In Finnish and Hebrew, these features occur in the subject position in the 1st and 2nd person, but not in the 3rd person. In both languages, the agreement paradigm provides independent evidence for such an analysis, in that the 1st and 2nd person agreement suffixes resemble the corresponding pronouns, but the 3rd person suffixes do not bear such a resemblance.